feat(data_structures): add oxc_data_structures crate; add stack

Cargo.toml

@@ -82,6 +82,7 @@ oxc_ast = { version = "0.30.5", path = "crates/oxc_ast" }
 oxc_ast_macros = { version = "0.30.5", path = "crates/oxc_ast_macros" }
 oxc_cfg = { version = "0.30.5", path = "crates/oxc_cfg" }
 oxc_codegen = { version = "0.30.5", path = "crates/oxc_codegen" }
+oxc_data_structures = { version = "0.30.5", path = "crates/oxc_data_structures" }
 oxc_diagnostics = { version = "0.30.5", path = "crates/oxc_diagnostics" }
 oxc_index = { version = "0.30.5", path = "crates/oxc_index" }
 oxc_isolated_declarations = { version = "0.30.5", path = "crates/oxc_isolated_declarations" }

crates/oxc_data_structures/Cargo.toml

@@ -0,0 +1,24 @@
+[package]
+name = "oxc_data_structures"
+version = "0.30.5"
+authors.workspace = true
+categories.workspace = true
+edition.workspace = true
+homepage.workspace = true
+include = ["/src"]
+keywords.workspace = true
+license.workspace = true
+publish = true
+repository.workspace = true
+rust-version.workspace = true
+description.workspace = true
+
+[lints]
+workspace = true
+
+[lib]
+test = true
+doctest = false
+
+[dependencies]
+assert-unchecked = { workspace = true }

crates/oxc_data_structures/src/lib.rs

@@ -0,0 +1 @@
+pub mod stack;

crates/oxc_transformer/src/helpers/stack/non_empty.rs → crates/oxc_data_structures/src/stack/non_empty.rs

@@ -132,7 +132,8 @@ impl<T> NonEmptyStack<T> {
     /// # Panics
     /// Panics if `T` is a zero-sized type.
     ///
-    /// # SAFETY
+    /// # Safety
+    ///
     /// * `capacity` must not be 0.
     /// * `capacity` must not exceed [`Self::MAX_CAPACITY`].
     #[inline]
@@ -253,8 +254,9 @@ impl<T> NonEmptyStack<T> {
 
     /// Pop value from stack, without checking that stack isn't empty.
     ///
-    /// # SAFETY
-    /// Stack must have at least 2 entries, so that after pop, it still has at least 1.
+    /// # Safety
+    ///
+    /// * Stack must have at least 2 entries, so that after pop, it still has at least 1.
     #[inline]
     pub unsafe fn pop_unchecked(&mut self) -> T {
         debug_assert!(self.cursor > self.start);
@@ -284,6 +286,11 @@ impl<T> NonEmptyStack<T> {
         offset + 1
     }
 
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
     /// Get capacity.
     #[inline]
     pub fn capacity(&self) -> usize {

crates/oxc_transformer/src/helpers/stack/sparse.rs → crates/oxc_data_structures/src/stack/sparse.rs

@@ -30,11 +30,16 @@ pub struct SparseStack<T> {
     values: Stack<T>,
 }
 
+impl<T> Default for SparseStack<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<T> SparseStack<T> {
     /// Maximum capacity for entries (either `Some` or `None`).
     ///
     /// Effectively unlimited on 64-bit systems.
-    #[expect(dead_code)]
     pub const MAX_TOTAL_CAPACITY: usize = NonEmptyStack::<bool>::MAX_CAPACITY;
 
     /// Maximum capacity for filled entries (`Some`).
@@ -44,7 +49,6 @@ impl<T> SparseStack<T> {
     /// Both are effectively unlimited on 64-bit systems.
     ///
     /// [`MAX_TOTAL_CAPACITY`]: Self::MAX_TOTAL_CAPACITY
-    #[expect(dead_code)]
     pub const MAX_FILLED_CAPACITY: usize = Stack::<T>::MAX_CAPACITY;
 
     /// Create new `SparseStack`.
@@ -70,7 +74,6 @@ impl<T> SparseStack<T> {
     /// * `total_capacity` must not exceed `Self::MAX_TOTAL_CAPACITY`.
     /// * `filled_capacity` must not exceed `Self::MAX_FILLED_CAPACITY`.
     #[inline]
-    #[expect(dead_code)]
     pub fn with_capacity(total_capacity: usize, filled_capacity: usize) -> Self {
         Self {
             has_values: NonEmptyStack::with_capacity(total_capacity, false),
@@ -187,11 +190,15 @@ impl<T> SparseStack<T> {
         self.has_values.len()
     }
 
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.has_values.len() == 0
+    }
+
     /// Get capacity of stack for any entries (either `Some` or `None`).
     ///
     /// Capacity is always at least 1. Stack is never empty.
     #[inline]
-    #[expect(dead_code)]
     pub fn total_capacity(&self) -> usize {
         self.has_values.capacity()
     }
@@ -202,7 +209,6 @@ impl<T> SparseStack<T> {
     ///
     /// [`total_capacity`]: Self::total_capacity
     #[inline]
-    #[expect(dead_code)]
     pub fn filled_capacity(&self) -> usize {
         self.values.capacity()
     }

crates/oxc_transformer/src/helpers/stack/standard.rs → crates/oxc_data_structures/src/stack/standard.rs

@@ -36,6 +36,12 @@ pub struct Stack<T> {
     end: NonNull<T>,
 }
 
+impl<T> Default for Stack<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<T> StackCapacity<T> for Stack<T> {}
 
 impl<T> StackCommon<T> for Stack<T> {
@@ -117,7 +123,8 @@ impl<T> Stack<T> {
     /// # Panics
     /// Panics if `T` is a zero-sized type.
     ///
-    /// # SAFETY
+    /// # Safety
+    ///
     /// * `capacity` must not be 0.
     /// * `capacity` must not exceed [`Self::MAX_CAPACITY`].
     #[inline]
@@ -154,7 +161,6 @@ impl<T> Stack<T> {
 
     /// Get reference to last value on stack.
     #[inline]
-    #[cfg_attr(not(test), expect(dead_code))]
     pub fn last(&self) -> Option<&T> {
         #[expect(clippy::if_not_else)]
         if !self.is_empty() {
@@ -167,8 +173,9 @@ impl<T> Stack<T> {
 
     /// Get reference to last value on stack, without checking stack isn't empty.
     ///
-    /// # SAFETY
-    /// Stack must not be empty.
+    /// # Safety
+    ///
+    /// * Stack must not be empty.
     #[inline]
     pub unsafe fn last_unchecked(&self) -> &T {
         debug_assert!(self.end > self.start);
@@ -182,7 +189,6 @@ impl<T> Stack<T> {
 
     /// Get mutable reference to last value on stack.
     #[inline]
-    #[cfg_attr(not(test), expect(dead_code))]
     pub fn last_mut(&mut self) -> Option<&mut T> {
         #[expect(clippy::if_not_else)]
         if !self.is_empty() {
@@ -195,8 +201,9 @@ impl<T> Stack<T> {
 
     /// Get mutable reference to last value on stack, without checking stack isn't empty.
     ///
-    /// # SAFETY
-    /// Stack must not be empty.
+    /// # Safety
+    ///
+    /// * Stack must not be empty.
     #[inline]
     pub unsafe fn last_mut_unchecked(&mut self) -> &mut T {
         debug_assert!(self.end > self.start);
@@ -265,7 +272,6 @@ impl<T> Stack<T> {
 
     /// Pop value from stack.
     #[inline]
-    #[cfg_attr(not(test), expect(dead_code))]
     pub fn pop(&mut self) -> Option<T> {
         #[expect(clippy::if_not_else)]
         if !self.is_empty() {
@@ -278,8 +284,9 @@ impl<T> Stack<T> {
 
     /// Pop value from stack, without checking that stack isn't empty.
     ///
-    /// # SAFETY
-    /// Stack must not be empty.
+    /// # Safety
+    ///
+    /// * Stack must not be empty.
     #[inline]
     pub unsafe fn pop_unchecked(&mut self) -> T {
         debug_assert!(self.end > self.start);

crates/oxc_transformer/Cargo.toml

@@ -21,22 +21,21 @@ test = true
 doctest = false
 
 [dependencies]
+base64 = { workspace = true }
+cow-utils = { workspace = true }
+dashmap = { workspace = true }
+indexmap = { workspace = true }
+oxc-browserslist = { workspace = true }
 oxc_allocator = { workspace = true }
 oxc_ast = { workspace = true }
+oxc_data_structures = { workspace = true }
 oxc_diagnostics = { workspace = true }
 oxc_parser = { workspace = true }
 oxc_regular_expression = { workspace = true }
 oxc_semantic = { workspace = true }
 oxc_span = { workspace = true }
 oxc_syntax = { workspace = true, features = ["to_js_string"] }
 oxc_traverse = { workspace = true }
-
-assert-unchecked = { workspace = true }
-base64 = { workspace = true }
-cow-utils = { workspace = true }
-dashmap = { workspace = true }
-indexmap = { workspace = true }
-oxc-browserslist = { workspace = true }
 ropey = { workspace = true }
 rustc-hash = { workspace = true }
 serde = { workspace = true, features = ["derive"] }

crates/oxc_transformer/src/common/var_declarations.rs

@@ -16,11 +16,12 @@ use std::cell::RefCell;
 
 use oxc_allocator::Vec;
 use oxc_ast::{ast::*, NONE};
+use oxc_data_structures::stack::SparseStack;
 use oxc_span::SPAN;
 use oxc_syntax::symbol::SymbolId;
 use oxc_traverse::{Traverse, TraverseCtx};
 
-use crate::{helpers::stack::SparseStack, TransformCtx};
+use crate::TransformCtx;
 
 /// Transform that maintains the stack of `Vec<VariableDeclarator>`s, and adds a `var` statement
 /// to top of a statement block if another transform has requested that.

crates/oxc_transformer/src/es2015/arrow_functions.rs

@@ -123,15 +123,17 @@
 
 use oxc_allocator::Vec;
 use oxc_ast::{ast::*, NONE};
+use oxc_data_structures::stack::SparseStack;
 use oxc_span::SPAN;
 use oxc_syntax::{
     scope::{ScopeFlags, ScopeId},
     symbol::SymbolFlags,
 };
 use oxc_traverse::{Ancestor, Traverse, TraverseCtx};
+
 use serde::Deserialize;
 
-use crate::helpers::{bindings::BoundIdentifier, stack::SparseStack};
+use crate::helpers::bindings::BoundIdentifier;
 
 #[derive(Debug, Default, Clone, Deserialize)]
 pub struct ArrowFunctionsOptions {

crates/oxc_transformer/src/lib.rs

@@ -31,7 +31,6 @@ mod plugins;
 
 mod helpers {
     pub mod bindings;
-    pub mod stack;
 }
 
 use std::path::Path;